1. Field of the Invention
The present invention relates to an optical lithography technique, and more particularly, it relates to a method of setting exposure conditions for optimizing parameters of a mask pattern and a light source, a method of manufacturing a semiconductor device using the mask pattern and the light source, and a program of setting the exposure conditions.
2. Description of the Related Art
Recently, a technique has been proposed which optimizes both illumination conditions and mask dimensional conditions at the same time to form a micropattern with high dimensional accuracy (e.g., refer to Jpn. Pat. Appln. KOKAI Publication No. 2004-312027).
Furthermore, a technique has also been developed to form a micropattern using a liquid immersion exposure technique. The use of this liquid immersion exposure technique enables the NA of a projection lens to be 1 or more, and it is thus possible to use an exposure unit employing ArF excimer laser light having a wavelength of, for example, 193 nm as exposure light in order to form periodic patterns having a half pitch of 50 nm or less (e.g., refer to Jpn. Pat. Appln. KOKAI Publication No. 10-303114).
However, the influence of mask dimensional error, in particular, dimensional variations within one mask tends to increase along with the miniaturization of patterns. The dimensional variations within one semiconductor chip increase if there is an increase in the variations of the dimension of a resist on a substrate per mask dimensional error, that is, an increase in a value generally called a mask error factor (MEF). Moreover, since this error can not be reduced by the adjustment of exposure, the yield of semiconductor devices is reduced (e.g., refer to Jpn. Pat. Appln. KOKAI Publication No. 2000-81697).
Thus, the influence of the dimensional variations within one mask tends to increase along with the miniaturization of patterns, and this error can not be reduced by the adjustment of exposure, so that a reduction in the yield of semiconductor devices is unavoidable. This can be avoided if the dimensional accuracy of the mask is sufficiently increased, but there is a limit to the improvement in the dimensional accuracy in a mask manufacturing process.